I have travelled many times to Colombia/bogota and agree with you. There are many low end places that are hit and miss.
So you should take my word of advice with the 2 agencies I recommended. There might be other agencies or places, but I know these two are consistent.
You could also try going to one of the high end strip clubs around the 82 with 15. Once I went there, talked to a girl for thenight and she gave me her number to txt her once I was out of the bar. They get into shit if their boss sees they are going away with a client. I txted her back and soent the entire night withher ata motel for only $125
She was gorgeous, but it happened to me once, so it is all about how lucky you can get.
Cheers!
V