FURIOUS WITH 3 MOBILE

Im beyond furious with 3. last month i topped up £35 to get the all in 35 add on (which used to only be £25 ffs) and it didnt convert to the add on so they did it for free and i got to keep my £35 credit which i kept to pay this months with. however, they failed to even inform me that my add on was expired and automatically went into my credit and used it. now i have no add on or credit to buy one. no money on me either as alot of my money has been cut. the worst part is my dad is actually critically ill in hospital at the moment and i need credit to keep my family in another country and my sister informed which i cannot do now. but i also need it for hotspotting my internet as i cannot afford an internet provider so i have always used the hotspot, and i need internet for college work ect.. i live chatted someone this morning about it and they were trying to tell me that i had purchased the add on last month and i had no credit. once i said that i had been checking my credit on the my 3 app often to make sure it was still there they soon changed their tune about me having purchased the add on and all i got was that they will contact me in 48 hours about a decision which will obviously be "Sorry we cannot help you". he offered 1gb of data. im sorry but that will last a day? not even? this is NOT OK to treat PAYING CUSTOMERS this way ESPECIALLY when they rise the damn price by £10 and theres people with barely any money trying to just get some damn internet ect and theyre just playing games with everyone.