Don't get acknowledged latter n bio

hi...I applied t4 extension in 16/03/2015 till date I have got any acknowledgedment latter or bio from the home office.i did special delivery and home office fees sent by poster order.i have receipt for both recorded post n made poster order from the post office.my visa was until 20/02/15 and applied before due date.now my question is..
1.my 10 years finishing on 20/10/2015 so till date my stay is legally count in long residence?
2.if ho received my documents in future so how caseworker treat dat?(my application invalid)
I m really worst situation last couple of month.i m chasing this situation with Royal Mail and home office.
Royal Mail sad u can claim money if u want.i sent copy of receipt ho and they sad we haven't received any thing.once we have any information we will contact u.i met soli he sad it is not ur folt..if anything outcome we will chase them.but I don't know wat to do?...I don't wan become overstayers..Evan my uni asking ab my visa ? But I can provide only receipt...my life going to spoil become of Royal Mail n ho....I need advice I really appreciate for help..I m stressful ab dat 2 questions ..I don't know I sud trust on soli or not...thanks

Any one plsssss...