Look, here is what you need to do to get out of this.
Find a new job. Your boss may very well be within his rights to not pay overtime. There are ways to get out of paying it. Not that it makes it right but it makes it legal in some cases. If you really want to pursue it, call the Labor Board.
Get a second job if you need to. I have had 4 different jobs to make ends meet. You do what you have to.
Wait on the tattoo. You do NOT need it! I have a full back piece that wraps around my sides and shoulders. I sure as hell wouldn't put that over my basic necessities.
Give the cat to someone who can care for it financially. Please do not de-claw the cat. It's just not necessary.
Call the credit card companies. They have programs for financial hardship. Most are willing to help you as long as you show them that you want to pay off your debt.
Make the minimum payments until you have enough to fix your brakes and get tires. Paying off sooner won't necessarily improve your credit score all that much.
Cut out frivolous spending. If you are an adult, then act like one. If you can't afford to go out to eat or drink then DON'T! Stay home, or better yet, get that second job.
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He came here for advice. If he can't afford to fix his brakes and get tires for his car then the cat should be given away. At this point, the cat is a luxury that he can't seem to properly care for financially. I love my pets as much as anyone but you gotta take care of you in order to take care of pets.
I feel for you. I really do. I paid for college out of my own pocket. No help from family. I got some loans but still had to work several jobs to make ends meet. There is more respect in doing the right thing. Especially when it is a hard thing to do. Get your finances in order then get a cat, tattoo, or whatever you desire.