Danny,
Macc Models is a one-man, four-days-a-week, operation that I have dealt with for years; mostly nuts and bolts, steam fittings, brazing rod etc. and always received the goods in short order. Any emails I have sent, have always had a reply.
I ordered a Graham Industries TVR1ABB engine earlier this year and it was dispatched promptly. On checking the contents, I found several screws (pre-packed in the USA) missing and advised Joe Poulton of the deficiencies by email. I got a quick reply saying that he would sort it out. After a couple of weeks had gone by without word, I telephoned Joe to discuss the problem and he advised that he was still waiting on Graham Industries to provide replacements. It appears that it is not a matter of Macc Models contacting Graham Industries who then pop missing bits into the post. Graham Industries, which I believe is another one-man business, has a shipping schedule and does not deviate from it. You want something in the UK? - You go in the queue and GI will sort it out when it's your turn.
To his credit and without prompting from me, Joe offered to take the parts from another kit and send them to me together with a reply-paid padded envelope for return of the original parts supplied. This duly happened and resulted in me being a satisfied customer again. However, it also left Joe with a kit he couldn't sell until he got the correct parts from Graham Industries. He could do the same for you but, if there is a QC problem at Graham Industries and we are not alone, then he could be left with several kits lying on the shelf which could not be sold. This is only conjecture on my part but I suspect there is some truth in it.
The signs are that the bottleneck - and thus the solution - lies with Graham Industries and Macc Models are at their mercy as far as shipments are concerned. I can only suggest that you keep (amicable) communications open with Joe Poulton who will do his best to sort the problem. He knows that small businesses like his can easily be damaged by bad publicity and it is in his interest to achieve customer satisfaction.
Regards,
Barry M