I had a lot of problems finding someone to balance my wheels as well. In the end I found a mobile guy who got hold of an adapter and did a good job. In order to fit the Matra wheels he had to put spacers behind the adapter plate using wheel weights, then the centre spindle didn't foul the inside of the wheel.
I tried ATS initially, but they just said that even though they can do centreless wheels and 98mm spacing, they couldn't make the wheels fit. I suspect that spacers behind their adapter could have solved the problem.
So if your balancer doesn't live up to expectations it's worth keeping the above in mind.
Except that DX702682 lives in California! So I don't think the U.K. ATS mobile will go that far.
Citroën cars also had wheels without a centre hole, so if you can find a garage that can service a Citroën, they should have a balancer that is suitable. Another possible way is balancing the wheels on the car, which actually balances the whole rotating mass, including hub and brake disc. We used to use these on-vehicle balancers on trucks, since their wheels and tyres are too big to put on a pedastal balancer. They work by having the wheel jacked up and just clear of the ground, and a sensor attached just behind to pick up the vibrations, and then the wheel is spun up by a motor driven wheel on the balancer rubbing against the vehicle tyre. Once spinning, you move the balancer back so it is no longer touching but it is picking up the vibrations from the sensor, and marking with a strobe light just where on the wheel it needs some weight and how much. Always did my Murena front wheels with one of these when I worked as a truck service technician and it worked perfectly! You must remember though to mark the relative location of wheels to hub/studs as it must always go back on the same, as it was balanced together with the hub.
There is a second consideration if you have a vibration from a front wheel on a Murena. You must check the ovality of the tyre and possibly the wheel first. It doesn't happen often with tyres, but they can sometimes be oval outside acceptable tolerance, which will be felt as a vibration when driving. I had this three times during my working career on various cars, and no amount of balancing would cure it.
Sometimes it is the wheel that is oval, and causing the tyre to appear oval, so if you have an ovality problem, you must dismount the tyre and check the wheel before condemning the tyre. I also had this once where a steel wheel was oval above tolerance. Once that tyre was refitted to a good (round) wheel, all was fine. Now in the case of the Murena, if it has alloy wheels which are relatively soft, they can become oval after driving through some really bad pot holes which we are seeing more of these days as they don't repair the roads as often as they should! So don't discount this, if tyre balancing doesn't rectify the vibration.
Roy