Pressure is mounting on Apple to address the ‘touch disease’ problem with the iPhone 6. Picture: Sean Gallup

A number of people have complained about the diminishing sensitivity and spotty functionality of the touchscreen on their iPhone 6 device as it gets older. With an unresponsive touchscreen the phone effectively becomes frozen and can’t be used properly.

The problem has been dubbed “touch disease” and according to the blog ifixit.org which coined the term, iPhone repair technicians are getting an increasing number of customers experiencing the annoying issue, which seems to be more common in the larger iPhone 6 Plus version.

Two lawsuits have been filed in Canada against the Californian-based tech giant over the issue while a separate nationwide class action lawsuit was filed in the US in late August complaining about the fault and even accusing Apple of covering it up.

Apple has so far declined to officially acknowledge the problem but pressure is mounting on the company to do something about it.

Three more US firms have signed on to the lawsuit against Apple since it was filed, meanwhile another lawsuit has been lodged in Utah over the engineering flaw, reports Motherboard.

Publicly Apple has been silent, however court filings show the company is aware of the legal efforts being made against it.

A recent filing by Apple shows the company asked to combine the two class-action lawsuits filed in the US.

“Given the similarity between the (Utah) and (California) actions, it would unnecessarily tax judicial resources if these actions were to proceed in separate class action lawsuits,” Apple’s lawyers wrote.

Earlier in the month news.com.au wrote about touch disease and was contacted by a number of Australian customers who had experienced the defect. Some had their phones replaced by Apple while others weren’t so lucky.

Aside from the obvious symptom of a frozen screen, touch disease is easy to diagnose because handsets will display a flickering grey bar at the top of the screen. The reason for this is that the two tiny “Touch IC” connectors, which translate the tapping and swiping of your fingers on the screen into a machine input, become slightly detached from the phone’s logic board. The result is often a progressive, and seemingly erratic, deterioration of touchscreen function.

According to AppleInsider, touch disease now accounts for 11 per cent of all Apple store repairs, eclipsing all other problems.