Bad bad service

On the 15th December 2014, my tenant called to say the sewerage drain was blocked. I contacted Drainmen and spoke with Gawie Kruger. I asked roughly how much would it cost to have a team go around and he said R200 call out fee plus R850 for the rotor machine that I asked for to clear the drain. The tenant called me to say the Drainmen had been and gone and the drain was no longer blocked. I then called Gawie Kruger again and asked for the invoice and all he sent was the banking details of Drainmen. I contacted him back to say I needed the invoice to know exactly how much I owed and still by the 18th December no invoice was received. I then made a payment of R1050.00 to cover the call out fee and the R850 for the rotor machine as discussed and agreed on over the phone. Then on the 20th January the credit control called to say I owe and additional R1372.50 for the work done. They told me an acid liquid had been used and not a rotor machine! I was then contacted today and finally an invoice was sent saying 5 litres of acid was used down drain and that it took 2 hours for the guys to pour it down at R800 an hour???? I will not pay for something I didn't ask for!!!! Bad service