Hi.. this last week I've been having fun starting my car. I know nothing so am going to have to find a helpful garage but wanted to ask the experts before I end up with someone changing allsorts and bankrupting me , any advice welcome..
last Tues I drove 15 miles , on my return was fine starting. Back home , stopped for petrol and would not start ( on the forcourt too

Nothing had been on.
AA man jumped it straight away , tested it and said it was a tad low in charging . Left it 10 mins and did a battery test where it cranked(sp?) for about a minute so loads of juice gone in.
He says battery is OK so may be intermittent alternator fault.
I had to go 90 miles on Friday...tried to start the car yesterday and totally dead again, jumped to get home and flat again today.
Guy who jumped it said it was charging fine so not alternator...No warning dash lights coming on .
Sorry to go on so long but my question is.....
Is it the battery or will I change that and then be told it's the alternator....I feel paranoid but as the AA man said it tested ok I don't want to waste money.
Thanks for reading