the platform you choose is pc or mac I don't think it'll really matter once you chose one just to get a hold of a live chat rep you can explain that to the rep once you engage in the live chat
now sometimes the issue for purchasing is to clear the internet cache and the browser that is used If say using google chrome then switching to IE or firefox can help
the EAHQ is about players helping players with gaming issues and is not a direct line/contact to EA so sadly I can't help you with this issue only the live chat reps can