citroen dispatch van brake problem?

My citroen dispatch van (1.9D, 05 plate, 56k on the clock) has just had the clutch replaced at a dealership garage, it turned into more complicated job when 3 of the 7 captive bolts had to be replaced when they dropped the subframe, (apparently they were spinning rather than coming out) some welding had to be done. After getting the keys back I drove the van out of the car park and having done that had to drive it back in because of a crunching feel to the clutch and a squeaking noise. Repaired in fifteen minutes, something to do with a bracket. drove van away, this time after getting home, I found hydraulic fluid dripping from the vicinity of the nearside front wheel. The following day at the garage, I was told it was unrelated to the work done, but upon inspection the mechanic found it was a connection to the ABS pump weeping. Removal of wheel arch necessary, tightened connection and problem seems to have gone. Now the problem I need help with! Having driven the van home I noticed that it wouldn't accelerate easily, and in neutral, with momentum down a slight incline, it ground to a halt after about thirty yards. Burning smell coming from nearside wheel plus smoke/dust coming out of wheel. Van returned to garage today and after being told it was the brake caliper, unrelated to any work done, the mechanic spent two hours fixing the problem, including bleeding the brakes. The van seemed fine after that for about 8 miles, then I began experiencing the same problem. The van struggling to accelerated easily, in neutral freewheeling lasting only a short distance and then quickly halting. This time though, burning smell strong on the driver's side, plus some burning smell from nearside front. I called the garage, I was told it was the master cylinder. I'm taking it in day after tomorrow, it's costing me £180-00p, which is on top of the £550-00p clutch replacement & subframe work. I'm struggling to see how the brake problem is entirely coincidental but would like help to see the solution. Please help!