You can get anti tamper torx from loads of places mate, I bought a cheap bit set from amazon that came with loads of weird and wonderful anti tamper bits, and yeah the maf is next to the air filter. Before you fork out for a new maf, try giving it a clean with some maf cleaner spray. If that doesn't work buy a genuine vw one. They ain't cheap but it'll work for a lot longer than an aftermarket one.
The air filter you put in, is it an oil based one (does it feel oily)? As these are a big no no for our cars, the oil from the filter gunks up the maf.