BIS BILLING

I took a top up contract in 2013 which was a Blackberry 9320 and it was supposed to be BIS inclusive on that particular promotion. It so happened last year in September when I went for an upgrade they never removed the BIS cause the phone does not use BIS as it an I phone 4s. I phoned customer service and I was referred to the branch to query this upon their investigation the initial consultant who sold the 9320 added BIS whereas it was inclusive on the promotion. I therefore need to be refunded the charges of that BIS for the duration of the contract and from the date of the upgrade to present. I have been phoning the branch and they are sending me from pillar to post about this and no one seem to care to give me any feedback.