Replying to Can ns help me out i want a dog

heres the deal i want a dog but my parents dont want me to get one. There reason is that they dont think im responsible enough. We had a dog when i was like 10 and i didnt really take care of it so itt ended up being there responsibility. Now there telling me since i didnt take care of it back then they dont think i will now. That was like 5 years ago and ive wanted a dog for a while now and im still getting this response. So if anyone had any ideas of what i could say to them to change there mind it would help out alot +k for good responses