The worst company that terribly disappointed me

I was in UK for 4 years and all this tine I was stupid enough to use this service. Despite it being overpriced I bought a contract sim and paid for it all the time. Then when it was my last year of university my contract finished and I had no intention of getting more as I thought I don't have a full year. But they told me that it would be okay amd they'd stop service in July. So I paid my last contract payment in July and left the country. I totally forgot about vodafone had more important stuff in my mind. Then it turns out they kept putting me in debt even though my sim was off and they werent going to stop till January. I called them to pay my debt and to stop the service but they apparently dont take foreign cards. To my question of how am I supposed to pay now she didnt even try to help with advise she just rudely asked " dont you have a uk card?" I explained I closed ot when I left. And asked her to tell me what else should I do. For which she got annoyed and told me to find a way and hang up. This. annoyed me as the phone call wasnt cheap either and I called them 3 or 4 times already trying to pay. I also tried to pay online but they have this all time problem with their website and online payments. The customer service is terrible. Vodafone is not worth it.