I signed up for a mobile and internet mobile modem for two years. The only way they would accept payment was by walking into a Nortel (Now called Yettel) shop front.
I tried using Bulgarian and many other fully operational and fully credited visa debit and credit cards but online payment was always rejected. I asked the Nortel staff, but they did not explain why payment could not be made in their online website and eventually just didn't answer or said no one speaks English in the company.
I had to leave Bulgaria for months to apply for a D visa in my home country. While I was away they sent debt collectors notice to my company address saying they would take court action to sell company property to collect the debt.
Has anyone had a more reliable experience with a Bulgarian mobile telecom provider?