Corsa D 1.2 Problem

[Del Boy]

My eldest has got a 2011 '11' Corsa D 1.2, last week his EML & ABS light came on and stayed on for a week, until it went into Vauxhall yesterday. Anyway, the fault was supposedly fixed and he picked it up today, was a right hand wheel speed sensor, they also found a misfire in the engine and 1 ruined spark plug. Anyway he rang me earlier and asked me to drive it and see how it felt, it is dangerously slow since they've touched it, he and I have noticed. Any idea what they could've done. Also he was just driving around and went from 30-10 MPH in second gear and the EML came on and was flashing until he picked up speed again?

[henryd]

It  needs a code reader with live readings to get some idea of whats occuring