Renault Megane wheels jumping to left when cornering

Not really sure what you mean by " Wheels jumping to left when cornering " but if it all started when the tyres were fitted you should have returned and complained immediately . If it was the front tyres that were replaced , try swapping with the rears .Check for broken front coil springs

The wheels turn left of their own accord and feels unsafe. The steering wheel also ends up at an angle

Your steering geometry / wheel alignment MUST be badly out of adjustment if steering pulling to one side and steering wheel now not central. .Could also have not been balanced out when adjusting tracking . Apart from being dangerous , it will hammer out you new tyres fitted . You need to take it to a competent garage to get wheel alignment properly adjusted .