Problems after battery change

[Amylouise211]

Good morning,

Hoping someone maybe able to help as I'll admit i'm totally clueless when it comes to cars.

Toyota Yaris Tr Vvt-I S-A
Year: 2009

Multi mode transmission with 50000 miles on the clock and absolutely no issues before a Battery change.

So my problems started last Thursday when I went for one of Halfords 10 points safety checks at the store. The guy told me my Battery was knackered and wouldn't last much longer so I decided to replace it there and then.

The Battery was put in by one of the Wefit mechanics at the store. Now straight after when I started the engine it cut out a good couple of times. The man checked the alternator etc said it was just the car needing to relearn idle point.

It was fine for the rest of the day and then cut out when I went to put it in reverse on Friday pulling out of a parking space.

I drove all day Saturday, absolutely fine.

I didn't go anywhere Sunday but did start the engine when I was cleaning it for its MOT on Monday.

Monday morning I went to start it and it wouldn't start at all. It took me about 8 goes to get it going.

Car went for its MOT which it passed with no advisories or anything. When it was there I said to the guy if he could check the battery. He said battery was fine/ voltage fine / wires all fine. He tightened it etc, checked alternator and said all fine.

This morning it's still not really wanting to start easily.

Idlepoint seems to be jumping between 0.5 and 0.7 constantly

When I'm driving it seems to be struggling to pick its gears as easily is before as well

There was absolutely no problems before the new battery is put in so I'm totally clueless!

Thanks