The number of written complaints to GP and dental practices in East Lancashire has risen over the past two years, according to NHS data.
Figures show that GP and dental practices in the East Lancashire clinical commissioning group (CCG) received 628 written complaints between April 2017 and March 2018, compared with 547 the previous year.
That's an increase of 15% - but medical experts say that there are many factors that could cause complaint numbers to vary year-on-year.
In east Lancashire, 34% of the 583 complaints that were dealt with in 2017-18 were upheld, meaning that evidence was found to support the complaint and an admission was made by the practice.
A further 13% of the resolved complaints were partially upheld. Complaints about multiple issues are recorded as partially upheld if some, but not all, of the issues are upheld.
Complaints that were found to be unsubstantiated, frivolous or vexatious and were not upheld made up 54% of the total.
According to guidance from the British Medical Association, a complaint can be made by a patient, or anyone affected by the action, omission or decision of the practice that led to the complaint.
Complaints can be made about any person working in the primary care practice, from the GPs themselves to admin staff and receptionists.
In recent years there has been an effort to make patients more aware of ways in which their views can be heard, including information on how the complaints procedure works.
Written complaints can be made about any issue, ranging in seriousness from a broken doorbell to allegations of malpractice.
Across England the number of recorded written complaints rose by 4%, from just over 90,000 in 2016-17 to nearly 95,000 the following year.
Healthwatch, the independent patients' rights group, said that the number of complaints can vary significantly from one area to the next.
Healthwatch policy director Jacob Lant said: "Numbers can also vary quite a bit year-on-year for the same areas, but this isn't necessarily a sign that services are getting better or worse."
He added: "In some cases, a large spike in complaints could be down to local efforts to promote how people can speak up about things they are not happy with."
Mr Lant said that Healthwatch is more interested in what is being learned from complaints, and how services are improving.
He said: "After all, that is the main reason why people complain in the first place, to make sure services learn and so others don't have to suffer the same poor experience in future."
The BMA said that while the rise in the number of complaints made against GPs nationwide was disappointing, it should be looked at in the context of the rapidly rising number of consultations that GPs provide.
BMA GP committee chairman Dr Richard Vautrey said: "The BMA estimates there are half a billion GP consultations in England each year.
"So whilst any complaint is regrettable, these figures represent a very tiny proportion of the patients GPs care for."
Nationally, there were more than 85,000 resolved complaints, of which more than 30,000 were upheld, and just over 10,000 were partially upheld.
Dr Vautrey said: "Where a valid complaint is made and upheld, we believe it's vital that a GP makes appropriate amends and the practice puts measures in place to make sure the error isn't repeated."
Professor Helen Stokes-Lampard, chair of the Royal College of GPs, said that it is through complaints that GP teams can improve the care they deliver to their patients.
She said: "Delivering safe, high-quality care is what all GPs and our teams strive to do. But if patients are not satisfied with the service they received, then it is entirely appropriate they make their concerns known.
"The GP-patient relationship is unique in the NHS, and GPs are consistently ranked amongst the most trusted healthcare professionals in the UK.
"That is a testament to the hard work and dedication of GPs and our teams, despite the extreme resource and workforce pressures they are working under."
NHS England said that it was working hard to help drive up the standards of complaints handling in primary care.
An NHS England spokesman said: "More than a million patients use the NHS every 36 hours, and while the vast majority are satisfied with the care they receive, we welcome all forms of feedback from patients and their families so we can continue to improve the services we deliver to them."