Issue with Dell Bluetooth mouse M787C left click

I have a Dell XPS 8300 desktop which came with a Bluetooth receiver dongle and a wireless keyboard/mouse combo. The mouse is an M787C Dell Bluetooth mouse.

The issue I'm having is notably with the left click of the mouse. When holding down the left click to drag something around or highlight something, it's as if the button is released and re-clicked intermittently. For example, say I'm trying to drag an icon from a to b on the desktop. I'll click on the icon, drag across and what will often happen is the icon is dropped before I release the button. Or when highlighting a text passage, half way through the drag, the highlighting will restart, i.e. so only the second half of the text ends up being highlighted. The frequency of the "re-clicking" seems completely random, sometimes this will happen several times in one drag (which can reaaaally mess up things when you end up moving 4 or 5 files around when you were only trying to move one).

A thought occurred that maybe it could be the Bluetooth connection being interrupted momentarily, so as far as the computer is concerned the left click was released, and then re-clicked. But I'm no expert, so I'm not sure!

Like I said, this is only noticeably affecting the left click, although it could be affecting other functions without me noticing as they aren't held down as often. Any help in resolving this issue would be massively appreciated as it's getting VERY frustrating!! Thanks! :)