If you want to just practise a certain shot or do your own workout, why not hire the Lobster Grand Slam V LE ball machine.

 

It holds 150 balls and you can set up to hit one shot repetitively, run through one of it's 6 pre-set drills or use the narrow, medium or wide sweep oscillation at intervals from 2 seconds to 10 seconds to hone your shots. It has a remote control so you can start and stop the feed, plus adjust the speed, spin, elevation and time without having to go round the net to adjust manually.