Judging the success or failure using any forum as the evidence is bonkers , generally folks that have a poor experience are more likely to be vocal about it , whereas the majority that have a straightforward successful order don’t join forums to say ‘Good job ! ‘ , so to base any opinion on what’s posted on here is no guide to the chances of failure.
As stated , there was a near identical post , that OP contacted BT not using the online ordering portal and apparently was given a ‘deal’ they took , AFAIR , it didn’t include migration to EE , but as EE are the preferred brand for domestic consumers, it shouldn’t come as a surprise that EE will probably have better deals to encourage consumers to move from BT voluntarily , that’s not to say every migration is a great success, it obviously isn’t , but there isn’t any contributor on here that knows the percentages , if the majority ‘failed’ or not even the majority but a high number, I’m sure that a pause would be introduced to fix the problem
FWIW , I relatively recently ( certainly after the announcement that EE were the preferred consumer brand ) re-negotiated my renewal and didn’t encounter any pressure to switch broadband or phone to EE , I did switch my BT mobile to EE but the deal was much better and I got my mobile data ‘doubled’ for being a broadband customer even though it’s BT broadband and not EE broadband
