Bad start to a new account

I opened my cotton on account as I was told 6 months would be interest free. My first statement came and interest had been charged.after numerous emails this has apparently been taken off...

Payment time came last week and I could not pay in store as this does not exist. So I paid via EFT, only to have a stop order which I never agreed to go off on the 1st.

I have had no response to several emails asking that this stop order be reversed as I have paid my instalment.