need help

As long as you have some way of knowing the letters to the collection agencies made it to them, you should be okay.
You can send a letter to the credit bureau and ask them to remove or change an inaccurate listing. Sending some proof would make the credit bureaus change it faster. There is a template in the DIY section under sample letters; letters to Credit bureaus.

Sending letters through certified mail is enough, as through this you will come to know whether or not the collection agencies have received the letters. As for the letters to the credit bureaus, you can send them dispute letters immediately after receiving the notification that the collection agencies (CA) have received the letters. This puts the CAs in a time crunch.

After you send dispute letters to the credit bureaus, they will ask the CAs to verify the debt. Now, before the CAs can verify the debt with the credit bureaus, they will have to validate it with you. Again they will have to verify the debt with the credit bureaus within 30 days, and if they fail to do so, the item will be removed from your credit report by the credit bureaus.

As for the paid of collections, can you tell me if the account status is showing "Paid"? Collection though paid stay on your credit report for 7 years. The only difference is that instead of collections, the account status will reflect "Paid collections".

It's good to know that you're handling the repayments on your own. It helps to save hundreds of dollars. Since you've the debt validation letters via certified mail, there's no need to send it again. Now, just wait to get the confirmation that the CAs have received the letters.

As soon as you get the confirmation, send letters to the credit bureaus and dispute the accounts. Try to attach any documents that you've as evidence. The bureaus will ask the collection agencies to verify the debts and if the agencies cannot do that within 30 days, the accounts will be removed from your credit report. Good Luck!!!