Impossible to cancel Telkom ADSL and land line

How is it possible that it is so difficult to cancel a line with Telkom? First it's almost impossible to discover the correct procedure to cancel, then you finally get it, only for Telkom to completely ignore it. I sent the written cancellation notice (per the procedure) to them, only for them not to acknowledge it and indeed keep on sending me bills for the coming month (you pay for lines in advance). So a warning to all considering joining Telkom: it's almost impossible to get out of it. I hope someone reads this and get it fixed!