Wouldn't necessarily count on it - I'm sure there's a contention ratio but the bandwidth being supplied is sufficient enough that even if the ratio is applied, you're within your subscribed bundle. It's in faster connections where contention ratios are more evident. But who knows! I remember once Nayatel telling me that I should be getting the full bandwidth since they don't use contention ratios.Also apart from this i learned that all VDSL connections are dedicated and their bandwidth is not shared among group of people. So a VDSL user should get full speed 24/7.
Bah humbug!
Anyway, if PTCL fixed your problem, then either (1) it's a fluke, or (2) they're taking customer support seriously. Any bets?