Banks have had their problems cross-selling superannuation to their banking customers, but these difficulties are minor in comparison to the struggle superannuation companies have had selling banking products to their super fund members.In July, Roy Morgan Research published the results of a survey that asked customers of the Big Four banks if they had their superannuation invested in a fund operated by their bank.Among personal banking customers, ANZ's superannuation cross-sell was 6.2 per cent, compared with 8.3 per cent for Commonwealth Bank, 9.5 per cent for National Australia Bank and 10.4 per cent for Westpac.Among business banking customers, ANZ's superannuation cross-sell was 12.6 per cent, compared with 13 per cent for National Australia Bank, 17.4 per cent for Commonwealth Bank and 19.8 per cent for Westpac.According to research published this week, only 2.7 per cent of personal AMP super fund members deal with AMP Bank. For AMP business super fund members the rate is four per cent.Roy Morgan asked industry fund members how many of them banked with ME Bank, which is owned by 30 industry funds. Only 0.7 per cent of industry fund customers deal with ME Bank.Roy Morgan's industry communications director, Norman Morris, said the superannuation industry has not built on the significant relationship it has with its members.