Contract not adjusted

I called Vodacom on the 21st of January requesting my early termination letter and the letter showed the handset amount a d contract amount. I didn't completely want to cancel my account so I paid the hardest amount which was R2438.98 on the 22nd of january and was advised that if I pay for the handset my contract will be amended from R250 monthly to R110 monthly. Last month my debit order didn't go through and when I called the call centre to find out why they said that my account is up to date. I went to a vodacom shop yesterday and I was advised that I owe R139 for the handset of which I have paid in full. I would like my contract to be adjusted accordingly and I will not pay the R139 and last month's debit order cos I called in and wad told my account was up to date.. May someone please sort this out...