i was with unicom for about 2 years . i had to sign for 3 years to get a good low price, i then had to keep checkin my bills as they kept upping them,once i threatened to leave then they reimbursed me,but not the full amount.if you dont mind keep checking your bills ,go with em, they are cheaper .
i insisted on a pay-by-cheque account and glad i did, they generally want direct debit only and i reckon itd be nigh on impossible to get them to pay a refund if they muck up your account
this was with a former business i had and when i closed this down,unicom wouldnt believe me and eventually i had to get my local citizens advice bureau to write to them ,and then they backed off