Contacting Amazon.de support by phone

Hello,

I know that contacting Amazon support by phone is more effective than using chat or email option. In this way you can avoid FAQ-type answers and get direct feedback. I would like to contact Amazon.de support by phone, but as I can see they only support German phone numbers. I am not German and my business is not located in Germany, so what mobile phone/internet service would you recommend to use to contact Amazon.de support? I need a cheap and supported by Amazon.de option.