Be very careful with "free linkedin credit," and giving them a credit card. Find in the LinkedIn interface where you can set the total spend you want on ads, as LinkedIn has auto-renewed card payments for ads without a notification equivalent to say, the ones you get for trivial things people in your network do.

Also, if you complain, they do communications not by email where you own the records, but via their user interface. I had a ~$300 ad spend balloon to almost $2000 and only caught it when I saw the credit card bill. They had been renewing the spend and charging the card without sending an email or regular account notification, as though to run it up before it was discovered. Their representatives commitment to repay the amount does not seem to have been fulfilled either.

When you are unsatisfied with being ripped off, they try to convince you that they are sympathetic to your incompetence, but they are keeping your money and you should be ok with that.

In short, avoid.