I suspect the problem may lie in getting staff to work on Sundays. Unless it’s agreed between the employer and employee and forms part of the employment contract there’s no obligation upon employees to work on a Sunday. Additionally, if the employee works in a shop, which the retail part of the dealer would be classified as, then, even if it’s in the employee's contract they work Sundays, they have the unilateral right to opt out of it at any time. If a shop employee does decide to opt out of working Sundays they can’t be penalised or discriminated against in any way by the employer. This matters not whether they are salaried employees or those paid by the hour.
I have to give credit to Ducati Carlisle ( J&L Motorcycles ) My Streetfighter was due its first service and the dealer I got it from ( Vertu ) quoted five weeks to get it in for a 600 mile service. That would mean I couldn’t use my bike for a month. I sent an email to them asking if I dropped the bike off one night could I leave it with them to fit it in. Didn’t even get a reply. I contacted Laurence at Ducati Carlisle and he gave me a choice of slots within a few days. On the day I chose the weather was awful but he said to bring it in a day later and he would squeeze me in. I didn’t even buy the bike from them plus I had been offered a free first service by Ducati which was meant to be carried out at the selling dealer. Laurence contacted Ducati and got them to allow them to do the service and updates so it cost me nothing and he would have to wait 6 weeks until Ducati paid him. He also installed the map for my Termi system while it was there. I can highly recommend Ducati Carlisle if anyone is wanting any work or servicing done. Plus they are cheaper than Vertu !