Telemarketing calls to follow up a direct mail campaign

We've been let down by our normal telemarketing provider. A direct mail campaign was sent out last Friday and needs following up now.
- Immediate start required
- 22 leads on Zoho, web based CRM with full instructions
- Leads are business owner who expressed interest to similar campaign last year and wanted call back 2018
- Sent letter and lottery ticket to warm them up and just need a few hours chasing to speak with them

Budget is:
£20 per hour for calls (1 hour per day if called twice during day to get hold of them)
£35 per appointment set
£35 is we secure business (we have over 50% conversion rate)