Terrible service and lack of proper resolution process

I made a car hire booking on the 4th of December. On the 23rd I went to collect the car at tempest and I was told they had informed travelstart that they have no cars and they had cancelled the booking on their side. Upon contacting travelstart on multiple times on the 23rd I have not gotten a response as to why the booking was cancelled and I was not notified of it. I made payment and the payment was not refunded. Now I’ve had to book a car that is more expensive and for a lesser days compared to my original booking. I have made contact with call centre again on the 24th and I was told I’d receive an email with details of how I should be refunded for the payment and the compensation for the higher cost that I’ve had to pay. This has seriously inconvenienced my budget. I made the booking through travelstart, whenever I follow up with them they keep referring me to their external service providers who’s telephones and emails do not work. There has been no interest from travelstart to resolve this. Firstly the chat service on their website is so pathetic and has few options of the type of queries that one can select. The telephone line listed there does not work. The email provided for the service provider who’s now apparently responsible for car hire does not work and the website chat is equally pathetic. It is so unacceptable to be inconvenienced like this when the payment had left my bank account.