Personally, if you have had good service from them before, then I would continue to use them.
Next time the van goes in for service, remind them to do the job properly this time, not like last time.
Always check their work before you leave. Check the dip stick. Is the oil clean, has the oil filter been replaced if yours is a screw on type you can see?
Ask for old parts, discs and pads for example, to be returned to you. Do a quick brake master level fluid check. Has the windscreen washer bottle been topped up? Is there enough water in the header tank?
Also write down the mileage of your van when you drop it off at the garage.
If they don't do the job properly the second time, then it's time to look for another garage.