Very strange. Doesn't sound like the Mtec that I've dealt with several times over the past few years.
I fitted their discs, front and back, initially to my 159 2.4 back in 2009. I was so pleased with them, that I subsequently fitted full sets to the 1750Ti that replaced the 2.4, to my wife's Giulietta, and they're currently designing a set for my Evora.
Always found them to be nothing but professional in their dealings with me, although admittedly, I've never had occasion to raise a complaint about anything.
Yes, I think that's the issue. They almost took it personally! The initial ordering process was fast and easy.
They've just tried to make the whole returning process as difficult as possible - virtually accusing me of lying. Obviously I enjoy wasting Saturday mornings changing discs and pads and spending lots of money in the process!
If you can imagine one of the disc faces - the thickness of the metal varied as you rotated the disc. Simple physics dictate that this cannot be flat/true. I may as well not have changed my discs. The warped/vibration sensation through the wheel under braking was awful and my heart sank. However - a much better story with the OE set-up. A different car.
They clearly don't want to refund. By sending out another set of discs without question sends a simple message to me. It says that they are aware of issues but it's cheaper for us to bung another set of discs out rather than refund as it's cheaper! However, the same difference in thickness was clear to see on these replacement discs and I refused to have them fitted.
Really, really disappointed. The MTEC discs gave readings of 0.12 and 0.15 run-out readings. This is acceptable to them but, clearly, the Giulietta QV doesn't like it. The OE discs are 0.02 and 0.03 (so virtually no run-out discrepancy to note). In these days of precision engineering and casting, I think that MTEC's tolerances are not acceptable at all. The proof was in the pudding. Also, if the disc faces vary in the consistency of thickness, how can the heat be distributed evenly. A total farce. The battle goes on.