Burning smell from Hijet



I’m noticing a burning smell coming from my Hijet every time I drive it. I just had the thermostat replaced and thermostat housing. The oil was empty and has now been topped up by a mechanic . It overheated and the problem was diagnosed as the thermostat having gone. Supposedly now everything should be ok and I’m told the oil will smell where there is spillages of oil burning off. I’m worried something else smells though -like wondering if it could be linked to the brakes? I feel like the smell stars to occur possibly the more I use the breaks

I live in Bristol if anyone knows any mechanics familiar with Hijets there

Anyone got any ideas?

Thanks in advance