Waiting 3 months for a winter jacket

On the 17th june 2019 took a jacket back to get exchanged for a bigger size , was told it would take 1 week as they had no stock . Waited 2 weeks and then gave them a call only to be told that due to the public holidays they were running behind on collections and deliveries . Waited another 3 weeks and nothing . gave them a call only to find out they sold the jacket that they got for me . They then said they will get one in about a week , almost a month later and nothing . I Then sent them a tweet and was told to dm them my details which i couldnt because they dont follow me ,. i did this twice and got the same msg back .