You can file a TCPA complaint [0] against Facebook for spamming your mobile number after you've instructed them to stop ("revoked consent"). There are a number of stories about TCPA around the web [1].

[0] https://consumercomplaints.fcc.gov/hc/en-us/requests/new?tic...

[1] https://www.forbes.com/sites/legalnewsline/2017/09/05/tcpa-d...

(IANAL, this is not legal advice.)