I still have a base trolly with swivel wheels. This is suitable for the built under ovens, as the hight of the trolly is about the same as the kitchen plinth hight, also wide enough to take the extra wide ovens. For the higher ovens, whether the ordinary single oven, double oven or the extra wide ones, I have a suitable motorcycle jack that I pump up to the correct hight, and pull out the oven onto it, then lower to be able to work on comfortably. Then re-raise height to slot back in.
However, now I am retired I no longer need these, so if any one may be interested in these, then please contact Admin who will give you my details. By the way, I would advise these items to be picked up, as I will be all too happy to show use of.
OT