|" I think I'll need to go back to a PC as this is my third laptop within four years."|
That is a pretty bad ratio, most get about 4 years on a decent laptop.
That said, unless you need it to be portable or are very cramped for space, a desktop is generally better, cheaper, more easily repaired, and often upgradable. If your needs are modest and you get or build a machine with decent quality components, you can get 5-10 years out of a desktop machine.
As mentioned, if you are comfortable with doing the work or are able to take it in for service, the ribbon cable from the motherboard to the monitor can be reset or replaced for a low to moderate cost and if it fixes the issues you may be set for a couple of years still. Even the monitor can be replaced and if the unit is fairly new, might be worth it. If you shop for replacements other than factory, make sure that the quality ratings is acceptable to you. There are those that are perfect and those that have small pixel areas that are 'dead'. These rejected monitors are sold off cheap and vary by the nature, location, and number of bad spots.
You have to be a little bit crazy to keep you from going insane.