Samsung Galaxy S II :: Email (Push) Stopped Working?

I have a Galaxy S2 and about a week before my contract expired I bought the Galaxy, all was well and everything worked and I was getting all my emails (I am on Gmail) direct to my phone and could view them using the Gmail icon on the front of the Galaxy. A few days ago my contract expired and I am now SIM only and everything has gone downhill since, basically push email has stopped, I have rung my provider and it's obvious that they don't know what they are doing because I have received about four or five different bits of advice/guidance from them and none of the options work. The first option was to set up another email address using the email icon on the Galaxy, I did this (with the same Gmail address) and it does work...but it's intermittent (the social hub is now showing this email address).The problem with this method is that I am sure that the two emails are clashing and push Gmail is still not working although I can retrieve emails via the refresh button (in other words pull email). Another member of staff at my provider claimed that he was an Android expert and he said that any emails sent to my Gmail account should be received by the phone, he added that the SIM card is irrelevant and that I should not have to have extra email bundles etc (which is apparently what I have right now although I did not ask for them). I have checked the manage applications route and I can't select a default email, the box is greyed out so it appears that neither of my email facilities have been selected as a default...is there a way to select default email? I reckon that I should delete the additional email account and try and get the push Gmail account working again....as I said both the accounts have the same email address. In addition although I have synched my calender no dates are showing on my Google email account on my PC, the dates were showing last week but nothing now, I have not changed any of my settings on my phone and the PC since the SIM contract started, apart from setting up another email account. Lastly I can't see a way to back up my phone on Kies Air (via Wi-Fi)..