Car parts and bikes seller Halfords is finding it an uphill struggle at the moment and slightly harder than analysts had imagined following recent warehouse disruption.Like for like sales fell 5.8% during the second quarter following a 4.5% drop at the retail business and 1.5% decline at Autocentres. Analysts were looking for 4-5%.That's a marked slowdown from the company's last update for the period 3 April to 26 July when it reported a 2.9% fall in like for like store sales and flat performance at Autocentres.Sales for the quarter on a like for like basis, excluding disruption caused by the switch to a new National Distribution Centre in Coventry, were down 4.9%.Interim same store sales were down 4.5% and off 0.8% at Autocentres for a total decline of 4.1, but bosses assume the annual decline will be nearer 3%.And though overall revenue came in 5.6% lower for the quarter and down 3.8% for the half, chief executive Damon Wild remains positive. "Halfords will deliver solid profit growth in the first half despite the challenging environment," he said Thursday. "We continue to improve our cost base and in the past few months have successfully addressed a number of company issues, such as the reconfiguration of our warehousing and distribution infrastructure."Although Wild is cautious about the macro-economic environment, he expects full-year profit growth to be within the range of market expectation, up 15.4% to £131m-138m.