"using oil while running in" is basically saying, f**k off for 6 months so when you come back we can claim the engine hasnt been treated properly for the last 6 months, not our issue.
The F4R does not use oil, i must have had almost 20 of them and the only one i had that used oil is sitting on the floor in the corner of my garage after my "smokey" 197 went bang.
Car straight back to wherever the work was done, as mentioned above, cars are a lot more complicated than a faulty kettle going back to Tesco. Don't use it, get it back to them, concerns in an email so there is history. agree straight away what the plan of action is. Don't be fobbed off with "we will change the oil and see how it goes"
Ive no idea who it is that you had the work done, but the chances are if they aint the best as has been hinted at, they will be more likely to refund you the cash and send you quietly on your way in which case you can have someone else put it right and you shouldnt be too much out of pocket.