Fabia Comfort 1.2 htp

Hi as the title says just acquired a lovely fabia in black.  Took it out for a drive and was fine initially then anytime the revs hit 3000 the power would be choked off. It seemed like a limp home mode. I took it back to the garage and they have changed the sensor on the crankshaft line but the fault is still present. We have been offered a refund if the auto electrician who is looking at it tomorrow cannot fix it.

We love the car and want it fixed. Does anyone know what this error could be ?