Misinformed advertising /wrong advertising

I have been using Uber for long now and never had any problems until yesterday. As it showed on my App that i will be receiving my 4th ride free for up to R100 when paying with my visa card and the offer was valid until yesterday 22nd April 2018 however there is no time added with this expiry date.. and according to my knowledge with any promo/reward when advertised with no time added but only a date the means that the promo/reward will end by the end of that specific date witch will then make it 23:59 on the 22nd of April 2018.. So i took a trip yesterday morning just after 8am thinking that it would be free cause its my 4th trip but i was charged iv contacted uber but they told me that the promo/reward has already expired. How? Its stil the 22nd of April ? And thats what i told them . After al this i was then told that the promo ended at 12:55am 22nd april so my ride was not free.. i refuse to accept this and told them so .. they have stopped replying to my emails, where im asking why the times wasn added anywhere ? And why i cant be refunded.