I can say with 100% of confidence, they oversell like crazy and are limited on both wireless spectrum as their pipes capabilities.
Even if they have much better coverage than Tmobile where i live and work, i will still endure it and not give them my service anymore.
 remember they charged extra if you had an iphone? ha! always used android and nokia. Also of note, they managed to overcharge my all-unlimited account for $800 above the contract for two consecutive months.