i had a 70 from BC, and somehow it was close to 71, when MOP rolled live blizzard turned on my XP without me knowing and i popped. immediatlely i did tickets. i was always polite and re-explained, as needed. i jumped on it right away before they would claim too much time had past.
went thru alot of blizzard GM's and escalated it to GM supervisors and customer service. they used canned responses many times unrelated to my ticket showing they do not read tickets or clearly understand or comprehend english with their outsourced GM's who deal with medical accounts, credit cards and road side assistance. you would believe this if you saw the answers i got...seriously
best part was that blizzard GM's and customer service flat out lied and said it could not be done.....note above where i said MOP rolled live
there were several players worldwide who popped 90 really fast that were rolled back, armories showed they hit 90, EU and US forums had threads of 90's who got rolled back, players no longer 90's wanting to know why, ex-90's having to contest de-leveling, other non-blizzard sites also had SS's, discussion and and armory links on their forums.
blizzard GM's continued to lie and said players could not be rolled back once leveled, when i referred them to samples from EU and US warcraft official forums/armories/achievements of it happening as i was trying to get my player fixed.....canned scenario response, not allowed to discuss actions being taken against other players
blizzard GM's also said they did not have the power to roll back players, this is actually a half truth/lie and deceptive answer. GM's can elevate the problem for consideration which i found out when i got past them
i kept pressing, made it past the lying blizzard GM's and GM supervisor's along with a honest admission, DEVs and programmer's can roll you back, but in my case they apologized and said they would not do it. they also told me to no longer continue reopening or starting new tickets on the subject.
you can try your luck with your 71, they didn't help me and it was their fault, i was not playing with XP on and off to do certain things.
imo, when the brackets go back to 70-79 for regular BGs in MOP, with gear squish +scaling will be less noticeable, players around 75-76 having a extra talent row at 75, plus abilities at 76+. along with a extra glyph may be serious OP vs a 70. the returning imbal the bracket. this could cause many 70's to no longer que random BGs causing a serious blow to the bracket.
there was a reason they split the brackets to begin with, because they could not balance 10 levels, just saying you are going back to 0x thru X9 with no info on balance appears to not fix anything, just a return to the problems they seem to forget they had on previous expacs