2007 Clio Cylinder 1 misfire and injector fault

hello everyone. I am brand new on here and need some advice.

my 2007 clio developed an injector fault, the car lost power but improved once I had turned the engine off and on again. I did a diagnostic check and got a cylinder 1 misfire code.

I changed coil 1 and 4 and added some injector cleaner to the tank.

Problem has not gone away.

Renault are going to charge me a fortune to fix.

Does anyone have any advice??

Thanks

Embo