Four months to make a shirt?

Not at all!

Full refund at least plus your fabric back (if she still has it) [ hmm]

It works out at something like a seem a week. I'd demand an explanation or my money back! x

She is way out of order, get on the phone and ask her to return fabric and shirt and give her a date by which it should be returned.

How long did it take to make a shirt on The Sewing Bee? This is nonsense. Demand your money , and fabric, back now.

I wouldn't give her any more time. Demand the immediate return of whatever she has be that a half made shirt or I suspect your untouched fabric.

Any unreasonableness is totally on her part, not yours.

My mother could make a shirt in a day. Something is dodgy here apricot. I would definitely turn up and see what's going on. I'd ask to be shown the shirt in its current state of readiness.

Send her a letter by recorded delivery that way she can't deny receiving it. Tell her that you require the shirt or the fabric and your money back by a specific day e.g. two weeks from the date of the letter. Say if you do not receive said shirt or fabric and refund you will take the matter further.