Gumtree and Defamation

Not sure if this is the right catagory for this post, if not, apologies.
A competitor has posted defamatory adverts on Gumtree. I have tried contacting them about the postings - without success.
Can anyone offer a little advice as to how to get in touch with Gumtree?

Thanks in anticipation.

Within the ad that is on gumtree, have you clicked on the report this ad button and entered details there?

gumtree

they generally respnd quite quickly

i noticed some porn and they repsonded quickly

Unfortunately, the individual is posting dozens of adverts, I try to list them seperately to gumtree but there is insufficent room. Its occouring on a daily basis. Each time I post an advert he gets it deleated as "duplicate" adverts, which tells me (I could be wrong) that its a computer program that deletes my advert. I want to send a solicitors letter to stop this. I have already instructed my solicitor to write to the advertiser and to issue injunctive proceedings if necessary.