Meriva A 2007 won't start

My car is a 2007 Meriva A, bought second hand in 2019, so frustrated with it. On Sunday just gone we were driving home and stopped at the traffic lights, the car just cut out, when my husband tried to start it again no lights would come on the dash, it would try to turn over but not start. The next day he looked on Google and found it could be a starter switch so he changed it with the mechanic next door, has been fine until yesterday (Wednesday evening) when it cut out on our way to college in the evening (drove fine no problems at all during the day) it did the same again but managed to get it started and get home after college. Today he did the school run no problems at all this morning, cleaned all earth ports, battery ports and tried plugging it in and no codes came up, we went shopping for around 2 hours, came back to the car and nothing at all works, but when we turns the key no lights on the dash, wants to turn over but won't start, hazards work, interior lights work but cannot start the engine, any one else experienced this problem? Or know what to do? Had to get it picked up on the back of a recovery truck