I never really have problems ordering spares from a supplier
The only time it becomes a problem is when the manufactorers are involved,then you can wait a while,only advantage is you know no one else can get it quicker
ordered a flue kit extention last year to take past balcony,took 8 days,they were having a stock check,the manufactorer,would not release anything till done 😱
Little story when Glowworm took over saunier duval to conquer europe!!yeh well,( strange how both products have nose dived)a few months later all spare parts for saunier duval dried up,glowworm closed the saunier duval parts center and said would deal with all parts though thier existing system,however the factory in france was sending faxs to them saying 'what parts do you require',but the fax's were in french and no body spoke french at the parts distrubusion center,so they just put faxs to one side,as you do,was'nt till shtf that management realised.🙁