I was banned for no reason. How to solve it?

I found out that my IP address was somehow banned. When i open certain sites, it tells me that im banned and marked as a spammer. I use email only once in a while and i almost never send emails. I also didnt spam any messages on these sites. I didnt even recive any massage that ive been banned. I know for sure it is IP ban. I tried to connect on other devices on these sites, but it tells me the same. When i connect from another location, i have access there.

When i checked if my IP address is on some blacklist, I saw on the list that im in blacklist of dnsbl.spfbl.net. It is a network looking for spammers and send their emails into spam folder a block them from recieveing emails. I dont have problems with recieving or sending emails though. If im not banned because of spamming emails, why some websites tell me that im banned and marked as a spammer and im
in their blacklist?

I alredy tried to contact them. I asked why am I banned, but they answered me that they cant help me, because the support is ony for email server administrators. I also contacted some webmaster on that site. Its more than a week, but i didnt get answer. I didnt find any informations about my ban or how long it will last. I dont know what else to try.