Credit card payments to Silhouette on-line shop

Hi I am a new member. I have a Silhouette Cameo and have regularly purchased from the Silhouette on line shop in sterling currency with my credit card. However, suddenly my credit card is not accepted and having talked to Silhouette America they inform me that it is an issue in trying to pay in sterling rather than dollars and can only suggest they change my account to pay in dollars. However my credit card provider will charge me to convert the currency which will make these very small shape purchases considerably more expensive. Silhouette also suggested I might try another credit card, but I only have the one.

Has anyone else experienced this problem and/found a solution please