Looks like you got charged extra for the cheapo cutter. Thats exactly what happens if you don't buy the Blair brand. The teeth break easily if you get the thing in a bind. Start cutting slowly for less breakage. No way to avoid all of it. See pic below for comparison, AES (top) vs Blair. Of course there are more expensive brands. You have another cutting edge on that one, just unscrew the toothy part and turn it over. Replacement cutters are available. Looks like you're doing the right thing with the drill from what I can see. Its normal to have to pry and maybe chisel the two pieces apart after drilling, especially on big structural welds. See vid below the pic for a demo of using the Blair cutter.
