cirtoen saxo jumping

I have a V reg saxo 1.1 and in the last couple of weeks it has been jumping and the engine is cutting out.It is impossible to drive as I cant control the jumping.
I had a new exhaust fitted and this problem started within a couple. I have no idea about cars so I need some good advice on what it might be so that I dont get ripped off when I take it to a garage

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