Is there any way to increase the 250 allowed block senders?

I am overwhelmed w/ spam. If I block all the all the spammers for a week or so I get noticeably less spam. but my inability to block only 250 addresses is not enough. I have to “free” the blocked addresses and they are back 15 or 20 a day. Is my only recourse to go to Gmail or duck.com? What a pain is Charter.