Appreciate you are asking about service but on the cost front use a price comparison website and look at the options for policies with a call out excess, most are cheaper there than on the service providers own site. There are some great deals to be had if you want a policy for peace of mind and rarely (if ever) use it. Can't recall the specifics but for instance Green Flag were about £30 with a £30 call out excess last time I looked, so you need to have at least 2 call outs each year before a conventional policy starts to be a similar cost.