It is as Jeffbb has pointed out. the ONLY way to get an increase in 'Upstream' is to migrate to ADSL2+ or pay a premium for a SDSL circuit (Upload speed is syncronous, the same, as the dowload speed).
Yes, a SSFP (Filtered Frontplate) can, and usually does, improve speeds by eliminating 'reflection' of the DSL frequency back down the PSTN frequency. In other words, the DSL circuit speed goes directly into your Hub/Router and nothing is lost and gains of up to 3/4Meg have been achieved. They are especially good for long-line issues. All SP's class an attenuation of 63.5dB to be the upper limit to guarantee stable broadband (even though we have a lot longer lines than that working on DSL), and yours is very close at 62dB.
I personally would ask you SP for a 'BROADBAND ENGINEERING VISIT' and ask the engineer if you are "On the best cable to the Cabinet". Explain your situation about the 'need for speed' and if there's a better cable (less attenuated) he would hopefully transfer you onto it.
2 things to bear in mind .... as mooted, you will never get above 0.5Meg upstream throughput speeds on your current package, even if you lived in the telephone exchange, so you need to migrate. Also, the 'better cable to the cabinet' may well be full due to other folk having the same problem as yourself. It really is a case of first come-first served i'm afraid. the sooner you ask for an engineering visit, the better your chance.
Best of luck mate.