There are different ways to work this. Highest interest bearing acounts are the ones that create the most problems for consumers. No creditors like to be put on the lowest of your priorities. The goal you have a is reallyl good one and youa re clearly focused on a solution, but first, perhaps you should look further than the end of this year concerning tyour future goals. THere are different strategies you can take depending on what your future goals are outside of paying off bad debt. If you simply want out of debt and that is your only goal, then my advice to you is to negotiate terms with each.
The others debts are larger than your 29% interest bearing account - but that 29% represents a problem in itself.
The other thing you want to safeguard yourself from is having them all start sharking you once they see you active in repayment participation.
I say this all the time - each person's situation is unique from the rest. Two people may have similar circumstances but the goals you set (current and future) are what has to be examined before any action is taken. It is like you can't walk over the bridge before you build it. You know what I'm saying here?
IF your goal is to get out of debt by year end, and you have the plan in place, and you have the tools to complete that goal to fruition, and that is all you want to deal with - then you are best to contact the higher interest bearing creditor you cited and see if you can negotiate a payment plan on the principle at least. It would not be a wasted effort by any stretch.
NEVER over commit to anyone. That will cause you problems, especially in situations like yours. If you over-commit then creditors who are chasing you for bad debt they will set the expectation based on the largest payment you make.
If you want me to help you with this it is really inexpensive and strategic to your personal goals. if you want to create pathways to reach different objectives.
I wish you well in your edeavors and I would love to see you succeed

. Please, let me and others know how things go!
Best,
Johnny