Stock stranded. Amazon changed ASIN

We run a small business. We had product variations, by colour. These had there own ASIN. Amazon created a new ASIN and merged these. We then had issues updating inventory details. Amazon proposed to demerge the ASIN. However we has stock in using the merged ASIN.. now the stock has arrived and Amazon staff do not recognise and won’t take the stock!! Seller support are unhelpful and 5 weeks have passed. Help!!