Was my car sabotaged at MOT? Mechanic's opinion please :)?

I took it to a new garage. Booked it in for the MOT, it failed but I kinda hit it off with the manager while it was being done so he did the required work for free AND only charged me half price for the test. Anyway, I ended up on a date with the manager, and we spoke about my car and the fact I havent had it serviced for a long time, he was really concerned and said I really need an oil change etc and I should book it in, so I did, for two weeks later when I got paid. Just over a week later, I broke down, diagnosed fault was 'no compression'. Im still dating the manager so obviously it went to his garage. There was severe engine damage from sludge and at one point it was looking like I needed a new engine. They sent off the cylinder head to be skimmed and pressure tested and had an engineer look at some slight wear to the cam shafts. Engineers report came back ok so it looked as though the engine could be rebuilt, rather than replaced. Then when they started working on it, piston 1 was dry, suggested an integrity problem with the bottom block, even though it had sat for three days and hadn't leaked at all. Back to needing an engine replacement. However, the manager wanted to do everything in his power to help me, and appeared to have already gone well over and above the call of duty. He said there was a chance the repair would still work and he would risk it, at his own expense, before saying a new engine was definitely needed. So the repairs appeared to work. He is keeping a close eye on it, checking levels every few days at the moment, but he seems very pleased with it and it is running fine. My final bill was half the cost of a reconditioned engine and included the engineer's work, labour, a head gasket set, a water pump, coolant, oil and filter, cam shaft bolts, spark plugs, thermostat and coolant. I am over the moon that I dont need a new engine. However, something has just entered my head and I know I am probably just being ridiculous but wanted an expert's point of view. When I booked the car in for the MOT, I filled in a form which asked me when car was last serviced. I put a '?' cos it has been so long. I am a young single woman and may therefore be considered an easy target. Is there anything they could have done during the MOT to make it lose compression a week later? They ended up with an 800 pound job out of it, and I know there are some dodgy garages out there. Maybe the whole thing, the manager's charm, his generosity with the MOT, his offer to take a risk for me to save me having to have a new engine .. could this all be part of a scam? Nobody could have done anything to the car, except for during the MOT and it was in there less than an hour, so I think I probably just am over-analysing .. and I know failing to change the oil for such a long time will, without a doubt, cause problems. I had sludge at my filler cap a year ago and ignored it (yes I know I am a complete idiot). The only thing which is making me slightly suspicious is the fact that it broke down just a week after the MOT. Coincidence?? ... Very interested to hear what people think ....