Terrible service

Bought a vehicle the 26th September from the silverlakes branch on the 6th October check engine light illuminated on the 8th of October took it to a workshop they said catalytic converter needs to be changed car stood there for a week *No transport for me* fetched the car on the 15th of October drove for sometime then on the 18th of November check engine light again car was collected on the 21st of November was advised the catalytic converter needs to be changed again to date i have no car communication is limited emails are ignored I don't have a car no communication no way forward this is the worst car sale I've ever experienced