Because this company has been your useful company, I would contact their Help Desk and indicate a concern that the shop was rejected because of non-response. Mention this as a concern for future communication rather than as an attempt to salvage the shop. Ask them for suggestions to keep this from happening in the future as you have checked your profile and the phone number is accurate, as is the email address, and you never got a voice mail and you have thoroughly checked both your Inbox and your Spam and find no notice. Ask them if, by any chance, they got the email returned to them as rejected by your email provider.
I would just eat the loss on the shop in question. The expenses you had in connection with it (but not the lost fee) is tax deductible against your shopping business. Be very clear your concern is for the future of your working relationship with them, not to dispute the past.
Be aware that if your email provider is AOL or Yahoo, these services have designated many of the shopping companies as "Spammers" such that emails are completely filtered and do not even make it to your spam folder. This is a major reason for suggesting that your shopping emails go through gmail.com