“Many PNC clients are having trouble connecting their bank accounts to their Venmo apps, cutting off their access to the popular mobile-payment system, owned by PayPal Holdings Inc. PYPL 1.78% When they have sought help, they have found the two companies blaming each other for the disruption. PNC Financial Services Group PNC 0.23% suggested in tweets that customers switch to Zelle, a payment app that it and other big banks operate jointly and that competes with Venmo.”