I too had a terrible experience last year ordering replacement parts.Impossible to get through by phone.E-mails were left unanswered even after many reminders.
I have to say that a few years ago I did not have any of these problems; seems to be something more recently.
What worked for me is researching the web for alternative e-mail IDs within Avalon (e.g. sales, marketing, management etc...) and send a reminder mail copied to all with the full history of reminders.
That did the job; promptly I got a response to my enquiry...
But even then they really make you work hard to get parts shipped overseas. They refuse to arrange on their behalf and include the cost in their quote so you have to organise shipping yourself. Not easy as USPS doesn't accept foreign credit cards.
Good luck!