Tata after sales service is the worst

I purchased a Tata Super Ace in 2016, the door lock drivers side was not working on delivery and I took it to Tableview Tata, they said they replaced it but by the time we collected the Tata it was not working, we were told to take it to Somerset West for another replacement, we did, left the vehicle there for 2 days only to be told to come and collect it as our part has been put into another vehicle and they do not have stock. we missed one of the services by 500km and we told to pay for it - this was the 20,000km service, we did. the following services we done under service warranty. We called Tableview for the 40,000 km service (12 times) to be told the service manager will call us back, never did (We had a very busy period and eventually decided to drive to Tableview Tata to try get the service done, only to be told that they no longer work on Tata and I must take it to Stikland Tata, I called to make an appointment and was given a date (Monday 8th October) to bring the vehicle in. I did, but by this time we had done 4 events in Herm**** as well as a few wine farms (Work had to continue) - the km reading was 45,100, Stikland said they would do the 50,000 km service under warranty which they did. The vehicle warranty expired in November. .. This was in October. We collected the Tata, drove from Stikland to Milnerton and used 3 lt of water, we called Stikland to tell them something is wrong and were told to bring the van back, we did. 4 days later we were told nothing is wrong we must collect the Tata, we did - another 3 ltrs of water to get to the office, called Tata again and instructed to bring the vehicle back, we did, again they called to say nothing is wrong. We collected and drove back, same thing happened - vehicle overheating - loosing water, we called for a 3rd time and were told to drive the Tata until the issue started and then bring it back... this is when they decided to start stripping the motor, first call was to tell me they removing the head to send to the engineers as they can see nothing wrong with it, second call was that the engineers require the block .... then they required the pistons. Please note that in this time (3 months) I had to hire a van at R500-00 a day (Cost to date R54,000) just before the 15th December I got a call from Stikland Tata to say my Tata was not covered by warranty as I had missed 1 service, also they can not find my service book. I know I paid Tableview in cash for the first and second service, the door issue is still not resolved. I have spoken to David at customer care as well as Sean, I am still hiring a van on a daily basis - and my Tata is now in pieces in Stikland. ********** (David and Sean) - I still do not have a report as to what caused this, the Tata was still under warranty when the motor issue started - and according to David the service and warranty are two different things. I need this matter resolved before I take legal action and claim van rental as well as repair costs.