Vodacom are cheats and then won't help!

I recently renewed my data contract with Vodacom. They quoted me a price inclusive of Vat and I have a copy of the written quote from them to prove it. I have just received my first monthly invoice after this upgrade, only to find that they have invoiced me the price quoted above, EXCLUSIVE OF VAT and have then added Vat onto this price that is supposed to be inclusive! Since then I have tried a number of telephone numbers that Vodacom quotes for queries, but I either get through to a Bot that is unable to assist me, or the call is cut before anyone answers!