Financial advice please?

I am a single parent and my son has downs syndrome i get ctc and wtc and support with his childcare costs he is in the same school that he was in before the summer when i was getting support  with chldcare costs but since september the tax credit office have told me conflicting information currently they are not paying towards my sons childcare even though my circumstances have not changed my son is 16 and is in his school until he is almost 20 and i have a full time childminder. My ctc and wtc has dropped by £80 per week and i am now in a position where i cannot afford to pay for my childcare because of the reduction. The tax credit calculator on the government website figure shows that i would get help with childcare costs but 1 advisor has told me i will not get any now he is 16 and the other has said i will but no payments have been made yes, has anyone come across this as i am beside myself with worry as i do not know what to do cant afford to pack in work due to having a mortgage.