As always, the answer is somewhat complex.
No, you needn't worry if...
- They're bidding for your company name, and it doesn't attract many searches per month. I have a client in this situation, but I know the company name attracts fewer than 100 searches per month.
- They're bidding for a key word anybody in your market might use. It's not your key word. Any anxiety you might feel when somebody else makes use of it is irrational and pointless (you may was well shout and scream at the weather for all the good it will do).
- They're bidding for your company name, and it attracts a lot of searches per month. As long as your site is set up correctly and your domain name is your company name, you'll always show up in the top spot in Google's organic search results (i.e. the left-hand side). Any money they're spending to show up in the paid listings is bidding up the price, making it increasingly expensive for other competitors to bid for that position.
- They're bidding for a trademark or copyright phrase. Talk to a law firm and see what can be done.
If this bothers you, there's little point letting it get you down. There are always ways to compete, and it's worth talk to a lead generation expert to see what can be done.