Thanks guys,
In the end decided to do it myself and sent the Mech unit to ECS testing, c.£500 inc delivery ans was returned within 48 hours.
Another £200 later for then oils filters etc. (the fact that Seat has the mech unit bolts in stock tells you something about this type of fault)
What in theory is a very simple job (if you say it quickly) one plug, 4 bolts for the cover and 9 bolts for the unit itself it probably took nearly all day to get it out.
Getting car level on jacks and ramps was fun, removing undertray and trying to undo the plug and the clip meant eventually having to remove the battery and airbox, (this did help with being able to get at the filter from above) then having to be very care with the small Torx bolts out it came, fitting of course was the reverse, new mech bolts but used the old sump (mine did not have the replaceable gasket).
Bought the fill tube from Ali Express, £10 well spent, did the oil and filter change, came to start the car and would not start!
Lots of errors when battery was reconnected cleared most but still would not start, had to reset the steering, end to end lock and then cleared faults with OBD11 still would not start, lots of head scratching and fearing for the worst, the problem as a voltage issue which led to the earth strap not being as tight as it needed to be (was removed for access) a bigger spanner on that and yeah it fired up.....
Not done many miles since but it has behaved itself with no errors
and the Mech unit comes with a lifetime warranty, hopefully will not need that, but as car is a keeper you never know.
Fingers crossed all is well!
