***Title should have read 58 plate Mitsubishi Lancer!***

I was just wondering if anyone could give any thoughts on this.

I have a 58 plate Mitsubishi Lancer GS3 petrol (not an Evo - just a bog standard Lancer). It has 100k miles on the clock, and so far it has been bulletproof during the several years I've had it. It's been regularly serviced and well maintained.

Around August 2017, it started to develop a knocking underneath, which was generally worse when driving on uneven roads and turning corners. I had it looked at shortly after this and no issues could be found. It passed it's MOT without any issues two months later. I had the knocking investigated again in December, but no issues found. The knocking has been getting gradually worse, and I took it to a garage last week to be checked over again when it also required new front discs and pads. Again, they couldn't identify the cause, even though the mechanic could clearly hear the knocking when he took the car out for a test after replacing the brakes.

My concern is that some big expensive problem is brewing and I can't seem to get it identified and fixed before anything happens. Three separate garages haven't been able to pin down the cause (four if you include the MOT test center) , yet the knocking is so loud you can clearly hear it over the radio, even if it is turned up quite loud.

I'm starting to wonder if I should think about trading the car in for something else, or cough up the money to get the local Mitsubishi dealer to investigate.