Billed twice for January

I got my January bill that was paid on 01 Feb that billed me for 01 to 31 Jan 2016. I have now received my Feb bill and guess what? It is for January AND February combined! So I upgraded on 8th of Jan, yet Telkom thinks that it makes sense to bill me for the FULL 31Days of Jan on my old plan AND THEN ALSO the FULL 31 Days of Jan on the new plan? So instead of 8days at the rate of R350/month and the remaining 23 days at R299/month I must not pay R350 PLUS the R300?! I refuse to do this as this is plain *******. Please can someone contact me as I would like this bill fixed TODAY!