Free and paid appointments in appointments+?

I have a free 10 minute appointment as a service in addition to paid 30 and 90min appointments. When I have payment required as 'no', the 10 minute visits work fine eg. confirmation sent, appointment registered as active. However, the paid appointments do not get sent to paypal.
When Payment required is set to 'Yes', the paid visits work well but the free 10 minute visits are set to pending and more importantly, the email does not get sent to the user. I have set the price for the free service as '0' and as a blank field. Can I get this to do what I want?