Public Liability Insurance

hi,
need some help/Advice, I am a Ltd company on agency work for 5yrs now, I thought the agencies I work for,that their Public Liability insurance covers me, but doesn’t so I got some quotes but I must be doing something wrong because the Quotes are £600+, I read on Trucknet I should get it for £50.
can anyone give me some names of brokers I can contact please

Sorry about the grammer but I am agency

I just payed £117 for £5m of cover.
Through google search public liability hgv ltd driver .It took me 5 minutes to fill in .I Got the Policy within 24 hours done and dusted .I used simply business through a comparison thing.

thanks beetlejuice I will give it a try