Unfair charging of interest and no feedback

Besides battling with Telkom to get a line i finally got one.<br> <br> Anyway Telkom messed up my address details on their system so I did not receive any invoices or statements in the post. Neither did I get any phone calls telling me how to pay my account. Basically I could not pay my account as I had no reference number. I even registered on their online portal and nothing helped.<br> <br> In January I then get a statement in the post. It was not even my address but somehow it managed to arrive. Very conveniently Telkom adds all the interest up for the 4 months. I then laid a dispute online as I felt it was unfair to charge me interest if I did not even have a reference number to pay. No response from this.<br> <br> Eventually I settled the full amount on the 28th of Jan and thought I'll claim the interest later to avoid further interest.<br> <br> Then today I get my February statement and I see Interest charges. How can I get interest charges on a ZERO balance?<br>