@Ala9clearly this is fustrating for you,
firstly, remember the host doesn't have to give more than their own cancellation policy, anything they give above that, is an nice extra, and should be treated as such, this is a individual person giving you back money, not a company.
Also a host can only refund the % of the money they recieve off airbnb, keep in mind that what you paid to airbnb is not what the host receives. All service fees go straight to airbnb and your host has no control or ability to get them back to you.
A Host agreeing to give back a 70% is an indiviual giving you back more than they have said they would. While the company (airbnb) is giving you back nothing... Remember they keep the fees.
If you want to make up the differance between the money you have got back vs the money you paid, i think your anger should be directed at airbnb, who have access to a lot more money than a host does, but has given you back nothing.
(The money came back via airbnb, but they didn't give you any of their portion back...)