Getting cheaper replacement option iPhone 4

Hi all,

I have a couple of problems with my iPhone4

1. Home button only works after pressing it about 6 times really hard (currently have the accessability enabled) and my biggest issue

2. Volume for music playback not working well at times

3. Wifi signal weak even when sitting next to the router.

I have tried all the standard things to rectify the above issues including vacuuming the charge port with no luck.

My question is this:

I will send it in for a replacement and am quite happy to pay. To choose the 'replace battery option' is around £62.44 and to choose the 'home button not working' option is around £126.44.

If the phone gets replaced anyway, could I choose the replace battery option for 1/2 the price when they replace the whole phone anyway???

Im not a total cheepo, and I buy apple products frequently for personal and business but naturally I would try to get away with the £62.44 option if I could.

I apprecaite any feedback and thoughts. Thank you.